What options are available for extending a Non-O visa stay in Thailand for a short visit?

Mar Ta it is a confused reply which I would like to remove if I was the admin. Your Mom does not wish to apply for a 1-year extension of the stay permit on Immigration, so there is no need to visit Immigration for anything. She wants to add a few weeks stay, and this can only be done by a border run

Mar Ta A "visa" permits and regulates the ENTRY into the country.

Depending on the visa category or “visa class”, you will receive different lengths of stay permits. For Thailand, these can be 15, 30, 60, 90, or 180 days. They can also be one year or 5 years.

The STAY PERMIT regulates STAYING in the country.

The duration of the permitted stay depends on the visa category with which you entered.

A single-entry visa becomes invalid upon entry and cannot be extended or used for another entry.

You have entered the country “on a visa” and you are now inside the country on a stay permit. This is also evident from the entry stamp:

This stamp states "admitted until" and a date. This stamp is the actual stay permit. This stamp is not a visa. The entry date is in red, and the expiration date of the "admitted until" permit is in blue.

In the upper right corner, next to the wording “visa class”, the visa category under which you entered the country is either handwritten or stamped.

If you leave the country before the expiration of your stay permit without a re-entry permit, the visa itself does not expire (because you no longer have any visa) it is just the stay permit that will expire.

@Mar ***

I've never been to the southern border, but I believe if you want to leave and return same day with visa exempt, you'll have to pay a "fee" of around 2000 baht at most southern borders.